Automatic telephone system.



A. H. DYSON.

AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED APR.15, 1905.

1,1 1 0,61 3, Patented Sept. 15, 1914.

8 SHEETS-SHEET 1,

A. H.. DYSON.

AUTOMATIC TELEPHONE SYSTEM.

- APPLIOATiON FILED APR.15, 1908 1,110,613, I Patented Sept15,1914.

8 SHEETS-SHEET 2.

A. H. DYSON. AUTOMATIG TELEPHONE SYSTEM.

APPLICATION FILED APR.15, 1908. 1, 1 1 0,6 1 3. Patented Sept. 15, 1914.

8 SHEETS-SHEET 3.

A. H. DYSONJ AUTOMATIC TELEPHONE SYSTEM.

' APPLICATION FILED APR. 15, 1908. 1, 1 1 1 3, Patented Sept. 15, 1914 8 BKEETB-SHBET 4,

A". H. DYSON. AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED APB..15, 1908- Batentedsept 15, 19M

8 SHEETS-SHEET 6.

W W 'Wg A. H. DYSON. AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED APR. 15, 1908.

Patnted sept.15 ,1914

8 SHEETS-SHEET 8.

A'. H. DYSOILJ AUTOMATIC TELEPHONE SYSTEM. APPLICATION FILED APR.15, 190a.

Patented Sept. 15, 1914.

8 SHEETBSKEBT 7.

foou o. 6 V 0.. 19 o, w 1! o e V 7 a e co v 9 q j u H. DYSON AUTOMATIC TELEPHONE SYSTEM. APPLICATION FILED APR.15, 1908;

Patented Sept. 15,1914.

UNITED STATES PATENT OFFICE.

ALFRED n. DYSON, or carcass, ILLINois, ASSIGtNOR, BY MESNE ASSIGNMENTS, TI KELLOGG SWITCHBOARD & SUPPLY COMPANY; A CORPORATION or ILLINOIS.

AUTOMATIC TELEPHONE SYSTEM.

' Specification of Letters Patent.

Patented Sept. 15, Ian.

' Application filed April 15, 1908. Serial No. 427,222.

ratus, and the means for working the same,

of a character suitable foruse in semi-auto maticor automatic exchanges, and I have illustrated my invention as embodied in an automatic telephone exchange system. I

My invention includes for its object the provision of certain operating features in volving the selective switches which 1 cmploy, and of the circuits in conjunction wit which said'switches are'employed. One objectofvmy invention is to provide a system ofcirc'uits and mechanism enabling me to use selective switches having groups of contacts arranged on one level as for .111-

. stance circularly, in conjunction with'which groups Wipers are employed, suitable ratchet mechanism being provided for causing long steps of the wipers to select different groups of contacts, and further-causing short steps of the said wipers from contact to contact of the selected group. A special improvementconsidered to exist in the present arrangement over those hitherto known consists in this, that a single driving magnet is employed to produce both the long and short steps of the ratchet and the wipers of the switch. The actuating magnet drives the shaft and wipers by an armatiire controlled pawl in the usual-manner, the long steps being effected by allowing the armature of the'magnet to make a long stroke thus ,driving the wipers over an entire group of contacts. 1 An auxiliary magnethaving its cir'c'u ificondition changed when a group has been selected controls a stop' which limits the stroke of the armature of the driving magnetwhen the short step travel of the .switch is required.

Objects of the invention are to provide a suitable. arrangement of circuits and mechanismfor controlling the driving magnet of the switch, proper arrangements for con trolling the operative position of the above referred to stop, and also the provision of suitable releasing or restoring arrangements when the switch wipers are to be restoredjto normal.

In organizing a system in accordance with my invention, 1. have provided, in addition .tothe first and second selectors, etc, and connectors whose functions are now so well lmown, certain additional-switches which I call line selectors which serve to select and connectwith the-calling l'nes, when calls are initiated over them, in order to place the directively operable mechan sm of the exchange in connected relation with the said calling lines. F or these;line selectors, as well as forthe first and second selectors and connectors, I: employ the above referred to lpng step and short step switches having a single driving magnet; and a further object of my invention is to produce a system embodying a solution of certain problems arising in the electrical control of switches of the described character when employed as,

line selectors.

Other features of 'the invention will be more particularly referred to in connection with more specific description and will be pointed out in the claims.

Referring to the drawings, Figure 1, con-- sisting of Parts 1, 2-, 3, 4 and 5 illustrates in diagrammatic form, circuits of an automatic telephone exchange system containing one embodiment of the invention. Fig. 2 illustrates a modified arrangement of line selector circuits. Fig. 3 is a front view of a long and short step svitch. Fig. at illustrates a side view of the switch structure, one magnet spool being omitted and 'a'portion of the contact bank being cut away to show the arrangement of the wipers. Fig. 5 illustrates a modified arrangement of the limiting stop. Fig. 6 illustrates a detail of the driving arm and pawl. Figs. 7, 8, 9 and 10 illustrate diagrammatically thearrangement of contacts and wipers when the switch shown in Fig. 3 is employed as a line selector. f z

As the circuit arrangement in Fig. l is drawn out, the system illustrated has a capacity of ten thousand subscribers'lines, first selectors F being provided for the purpose of selecting the thousands. second, selectors G for selecting the hundreds, and connectors H for selecting the tens and units.

I preferably employ one hundred point switches having :their contacts arranged in ten groups of ten contact sets each. Assuming ten thousand subscribers lines,- as called lines, the lines would be divided intendshundred groups of one hundred lines each,

I and each such group on the usual per fcent trunkingbasis would be provided with their multiple called contacts appearing in the banks of ten connectors. The group to which any line as a called line is assigned,

, will be determined by the directory number which the line bears, so that all the lines havin'g their multiple called contacts at a group often connectorswould have directory numbers of the same hundreds value.

' .-;Further, the multiple called contacts of the :one hundred lines at their assigned con- "'i'lctor's would be arranged in ten sub-groups T of ten contact sets each, the position of each such -sub-group as to the serial order in which their contacts will be engaged by the Wipers of the connectors being determined by the tens valuein the hundred.

r "-For the on e hundred groups of called lines there' will-,""therefore, be one hundred groupsof te'n connectors each, making a thousand connectors in all. The one hundred connectors for the ten one hundred line groups constituting the first thousand lines aofor the first hundred of the first thousand will constitute thefirst group of ten .contacts of each secondselector forthat thousand; the contacts for the connectors for the second hundred of the first -thousand will constitute the second group of contacts of'the second selectors for that thousand, and so on for the other groups for the first thousand. Corresponding connections will be made from the different groups of ten connectors of the hundreds of the other thousands to" the second selectors assigned to those thousands. on the usual ten per cent trunking basis, there will, of course, be one hundred second selectors G for each thousand of the ejclr nge and-the contacts of the connectors will therefore, if uniform multiplying be mgcrved -lfii multiplied one hundred times, once at each second selector for the respective thousand.

. Each second selector G. is provided with multiple contacts 161, 162, 163 appearing in the banks of first selectors F, which first selectors are, of course, common for connection with all subscribers in the exchange.

' Qn a ten percent basis there would be one thousand first selectors F and each such -first selector would have before its wipers 158, 159, 160, ten groups of multiple-con- }tacts, the contacts-of each group being con- "Lf'BOfneCtedto the second. selectors G for a differeut thousand. .There being one thousand igfirst selectors F" and one-thousand second,

"selectors G, there willbe a total. ofone hundred thousand'multiple contact sets 161,.

162, 163 at the: firstselectors, so that each second selector G will have its contacts multiplied only at one-tenth of the first selectors F in the usual course of multiplying.

Each first selector F has permanently joined to it a line selector E before whose wipers 2--2526 appear multiple contact sets 182S-29 of one hundred lines, which sets of contacts may be called multiple calling contacts. The lines of the exchange as calling lines are'divided into groups of one hundred and on a ten percent basis, themultiple calling contacts of each one lumdred line group will be multiplied before the wipers 2-2526 of ten line selectors assigned to that group of lines as calling lines. Further, the multiple contact sets of each one hundred line group would be divided into ten sub-groups of ten contact sets each, and when any calling line initiates a call, a line selector E 'will operate tfo select the group in which the calling line has its contact set included andthen will pick out the indi idual multiple contacts of the calling line whereby the line selector E will have caused its paired first selector F to be opm'atively connected with the calling line. After this, directive impulses will be transmitted from the calling line to cause the firstselector to pick out a group of second selectors for the wanted thousand and then an idleselector out of such group; thereafter directive impulses will adjust the selected. idle selectors to pick out the group of connectors wanted and then an idle connector out of such group; whereafter the selected connector will be adjusted to pick out the required group of lines-and then the required line out of such group.

In the diagram. Fig. 1, Part 1, I have illustrated a calling substation A. connected by the line conductors G6 and G7 with a suitable line circuit arrangement at the exchange. The substation at A includes the customary hook .\'\'ltCl1 59, normally holding the call-bell in an operative bridge of the line limbs and, adapted, on the removal of the receiver, to be lifted, disconnecting the call-bell and operatively connecting the talking set with the line. A calling device or dial 65 is provided, said calling device being normally locked by a pivoted pawl .d-ial 65 has attached toiit suitable teeth of' iusulatingmaterial which control the connections of the impulse springs 62 and 63,

whenthe .dialis at normal, as shown, holds "th ring 04 disengaged from its associated and the said dial also carries upon its lower' part a stud of insulating material, which,

spring. When the dial is rotated' by hand in the direction of the arrow, the said stud frees spring 64 which, by its tension, engages its contact and makes connection with ground. l/Vhenreleased, the dial rotates back to normal and when it reaches this point, the said stud restores spring or to 7 its normal relation shown. It is obvious that the rotation of dial 65 in the direction or the arrow has no operative eilect upon "theysprings 63 and 62. lVhen, however, it is released, the teeth of insulating material operate to momentarily open contact 63 as many times as there have been teeth brought below said spring. After the last tooth passes above spring (33, the tooth at the extreme left causes a momentary opening of contact '62 whereafter the calling device 1 reaches normal and its motion is arrested. While the openings of circuit were being made at contact 63 in the line limb 67, it is apparent that line limb 66 will be connected through contact 62 to ground through the contact of spring 6%. Conversely, when the circuit of limb 66 opened at contact 62, limb 67 will be grounded through contact 63 and spring 64. Also when the calling device reaches normal, a conductive bridge of line limb 66 and (37 will be estab- Snlished through the substation before contact 51 is 6pened,,it being remembered that the dial 65 is only operable when magnet 67 is energized'and magnet .30 can only. be energized when hook switch 59 is in its alternate position.

Itis thus apparent that by the operation of the .dial 65, a calling subscriber can cause a number of sets of openings of line limb .67 at contact 63, while line limb 66 continues grounded, each set of openings of line limb 67 being necessarily followed by one opening of-line' limb 66,- while limb 67 remains grounded. By successive.actuations of the dial 65, the calling subscriber is enabled to count out the digit. comprising the number of the called subscriber. and the various openings of line limbs 66 and 67 cooperate with the directively operable switches at the exchange in completing the connection with the called-for line.

As before indicated, the lines as calling lines, are divided into groups of one hundred by having their multiple contacts grouped at the exchange before the line selectors. The ten line selectors E for each such group of one hundred lines are preferably not constantly operating devices, but are normally at rest, their wipers having a fixed or normal position. For starting an idle line select-or E when a call is initiated, a master-switch mechanism D is provided, one for the one hundred lines, including wipers 80, S1, 82, having'be'fore them contacts 83, 84, 85, one such set being provided for each Each line of a group has its line relay l3; and a common conductor 73 is provided, connected to the master-switch relay 73 and having branches, one to each of the line relays of one hundred lines whereby any calls ing line of the one hundred may control the master switch D to start an idle line selector. Each line, in addition to its line relay 43 indi'ridiial to it, has its cut-off relayol, the latter being employed to render the line relay inoperative when the line is connected with.

As before indicated, the multiple contacts 18, :28, 1-9, of the one hundred lines of a group of calling lines, are divided into ten groups of ten contact sets each at the line selector. banks, whereby the one hundred lines are divided into ten sub-groups of ten lines each. Each such subgroup has a subgroup relay 4T, 47* or H etc., and a subgroup contact 31, 31* or 31, etc., appearing bei'ore the group selecting wipers 27 of the line selectors F4. The group relay l7 of each sub-group has an armature l9 controlling the electrical condition of the group contact 31 and an armature 48 which coiiperates with the constantly traveling interrupter I and with the 1nasterswitch mechanism l) in starting an idle line selector- E. Each such group relay l? is connected. by a, common conductor 50 having ten branches, one extending to each line relay oi its sub-group, so that the line relay of any line of a sub-group can control the respective group-relay.

The common interrupter I is provided having two pairs of segments (ill-69 and 7l.71 and the grounded wiper 72 is constantly traveling over the segments at a rapid rate, successively grounding them.

The segments (39 and (35) are connected to a common conductor 38 which has branches extending to armatures 108 of the relays 10-; of the different line selectors E and the interrupter is employed. among other uses, 1 to transmit current-s over the conductor 38 to operate the windings 10 of the driving magnets 10 to produce the long step travel of the switches" E. In order to prevent a winding 10 from being actuated by a partial impulse over a wire 38, whereby but a partial long step of a switch ll might. be produced. the circuit at each switch E is so arranged thatits relay 10 which controls the contact IOS'in/the circuit of winding 10, can be actuated only by current through one of the segments 71 or T1 of the interrupter I.- ,By this arrangement, no current can be passed through a winding 10 upon the energization of the line relay 43 of a line and the consequent energization of the respective group relay; until the wiper 72 engages a contact 69 or 69 after having first been in engagement with the contact 65" line selector of a one hundred line group.

.71 or 71, to operate the relay 104, since the line and group relays were operated, whereby such operation of the line. and group relays, which may occur at a time when the wiper 7:2 is about to pass ofi a segment (i!) or 69. is ineffective to produce a wrong operation of the line selector E by causing it to make a partial long step.

Before going more specifically into the description of the circuit diagram, the..preferred mechanical arrangement of the switch will be referred to. As indicated in Fig. 3, ten groups of ten contacts 18, 18. 18", etc., to 19* are provided arranged in a circle, making one hundred of suchcontacts, while between the group of contacts. contacts 19, 1! etc.. to 19 are located. A rotary shaft 7 is provided suitably journaled, as indicated in Fig. 4. to the circular base plate 8 and to the bridgeSupon which shaft are mounted the wipers m. n, o, s, and the ratchet wheel :20 which of course has one hundred and ten ratchet teeth.

The magnet 10. whose spools are mounted upon the bridge 8. has a pole piece 2+. connecting the upper extremities of the. cores,

.and through this pole piece extends a slotted stud 23 with which is associated the friction piece 23 and the screw 25 threaded to the piece 23, the whole furnishing a convenientmeans for adjusting the tension of the spiral spring 21, one end of which is attached to the end of the armature 3 to the stud 23. The armature 3 is supported by the auxiliary' shattl which is journaled to the wiper shaft 1 and to the stud The spring 21 serves of course as a retracting spring for the armature after each actuation of the magnet 10,.being adjustable as de scribed. The core of each spool of magnet 10 has. at its end adjacent to bridge 8. a pole piece of the shape indicated at 9, the transversely disposed armature 3 having the projections shown. best in Fig. 3. extending to proximity with the respective concavesurfaces of the pole pieces 9. the whole producing an arrangement well calculated to give a strong initial pull upon the armature 3 when magnet 10 is operated, permitting along with this, a relatively great movement of the said armature. An adjustable stop 4 is provided to limit the back stroke of the armature away from the pole piece. The arm 6 carrying the driving pawl 6 which is provided with a suitable spring to hold it in engagement with the ratchet as indicated in Fig. 6, is fastened to the armature shaft 1 so as to partake of the rocking movements of the armature. the pawl 6 being by them effective to drive the ratchet wheel 20 stepby-step. The adjustable stop 12 is provided threaded to a projection of the piece 13 which is fastenedby the bolts 15, 16 to the circular bank of the switch, 'and the said stop serves to limit the length of the stroke of the pawl 6 and of the armature 3 when and the other while the switch is performing its long step travel. The piece 13 also has a projection to which is suitably pivoted the pawl 7 which engages the teeth of the ratchet 20 and serves to pre-. vent back movement of the ratchet which mightotherwise occasionally occur from the jar occasioned by the armature 3 when forci bl v retracted by the spring 21 at thelconclusionof one of its long strokes. The pawlcarries a pin engaged bythe arm 6 sothat when the latter is fully retracted, the two interlock and the pawl 7 is forcibly held engagement with the ratchet 20. A further important functitm of this arrangement is to, render impossible a between-contact position of the wipers. Thus, if the pawl 7' is',' at the time pawl'fi is retracted, not engaging a full tooth of ratchet 20, the impact of arm 6 will force the pawl 7 to fill thetooth upon; 'T whose surface it rests,-whereby the wiper's '85 will be carried back to one of their definite operative positions.- Upon the piece l3is mounted the stop magnet 14, controlling, by its armature, the stop pawl o'which, in the line selector Fig. 3,'is shown as below the pawl 6 being therefore normallyout of engaging relation therewith. The said stop pawl 5 abuts upon the projection 17 of the piece 13 and when the magnet 14 is energized. is brought forward so that its upper extremity is in the path of the pawl 6", thus limiting the stroke of armature 3, piece 6 and pawl 6. 1 v I It is now apparent that when magnet 1% is dccnergized,actuation's will. by pawlG, produce long steps of the switch wipers. and f01- 1Cl1'S11Ch long s'tep,- it will be understood that the wipers willbe moved from a position engaging a. betweengroup contact 19 over an entire group of 105 contacts 18 to engagement with the next between-group contact 19. Thus,to select the group of contacts 18 for instance, three actuaticns of the magnet 10 will be produced= wiper m and the others will then have'advanccd three long steps torest-in a position where wiper .m engages the contact 19. \Vhen, now, magnet 14 is energized, tli'e-:1.-,.

' movable stop 5 is substituted for the stationary stop 12 as the member limiting the circle of travel.

For the first and second selectors and for the connector, the stop magnet arrangement indicated inFig. 5 is. preferablyem'ployed, the said arrangement being one in which 9 of the magnet 10 00- magnet 14' .remains inert and the tion with the pawl iVith this arrangement, in order to secure long-step travel of the switch, the magnet ll must be energized to withdraw the stop pawl 5 from the path of pawl 6 and then when short step travel .is to be produced, n'iagnet 14 must be denergized to allow the stop pawl 5 to assume its normal engaging relation.

This arrangement is, in some respects, a preferred one, slnce 1f, the pawls 6* and 5 be both made of magnetic material, thereis a' slight tendency to stick or freeze when the two pawls are in engaging relation, magnets 10 and 14 being simultaneously energized.

Making one pawl of non-magnetic material or providing an gap spacers of course ob-- viates any such effect.

While I hare, in Fig. 1, at E, shown th e circuit closers or wipers 2", 2, '25, 26 and 27 diagrammatically, as connected directly with the conductors of the line selector E, I have preferred, in the mechanical switch structure, to terminate the conductors, shown connected to the said wipers in Fig. 1, in stationary contacts while the switch wipers. themselves in the mechanical structure hare, in themselves, no circuit connection. but act merely to close conductive bridges between bank contacts with which they are associated. The electrical equivalency of the arrangement shown in Fig. 1

to those shown in Figs. 4, 7. 3, 9 and 10 will be apparent. In Fig. l, five sets or pairs of wipers m, n, 0, p and s are indicated,

mounted one pair above the other upon'the main switch shaft 1. Referring now to Figs. 7 to 10 inclusive, when the wipers are in their normal positions, they will be engaging respectively the contacts 86, 87, 8S and 31. By referring now to Fig. 1, it will he apparent that when wipers m are in their normal position,,they clpse the otl-normal contact 86 to its associated contact, thus producing the normal circuit condition of contact 86 shown in Fig. 1. Similarly, when wipers n and 0 are in their normal positions, they close respectively the oft-normal contacts 87 and 88 to their respective associated contacts as indicated-in Fig.1. It is also apparentthat when shaft 1 is caused to make its first step, each of these olf-normal contacts 86, 87. 88, wil.be opened, wiper n then closing the oft-normal contact 89 to ground, the said contact continuing closed to ground until the wiper has completed its revolution and is restored, while the other elf-normal contacts remain open until the line selector reaches normal.

The private wiper 2 indicated in Fig.1" in its mechanical embodiment-fasshown .in Fig. 7 represented by the jc onductipely joined segments 2, while the contacts 18, are those adjacent to the said segments. The ibeilween-gronp contacts 1-9, etc., are plainly indicated in Fig. 7 and the wiper 2 is rep resented by the contact 2 of Fig. 7, whereby the wiper-m, in a between-group position, conductively bridges or closes a contact lQ- Z in Fig. 9. the common strip which extends circ-ularlxcomplete. except for the break at the otl-normal contact 8b, repre seuts the wiper 25 while its adjacent sets of contacts '28 represent the multiple contact of Fig. l and the samearrangement as that shown in Fig. 9 is employed for the wiper '26 and the contacts :2 as indicated by the alternate reference characters given in Fig. 9. The ring 27 in Fig. 10 is the equivalent of wiper 27 in Fig. 1. 'Iheaviper a has a between-group position closing contacts 27-31. 2T :31" just indicated in Fig. 1, while the grounded segments of Fig. 1, Part 2 are plainly indicated in Fig. 10.

It will be understood that switches of the general character shown in the mechanical figures are used for the first and second selectors and connectors, commons being employed for the wiper contacts shown in Fig. l, the switch wipers thus being, as in the case of the line selector, without circuit connections in themselves and being used to cross the commons to the private contacts and the line contacts. The oil-normal switch arrangements of the first selector, second selector and connector will be secured in the manner obvious from the description given of the oil-normal arrangements of the line selector "and need not be specifically referred to.

The detail oi the circuit arrangements of Fig. 1 will best be understood when explained in connection with a description of the operation of the system and will now be described. it being assumed that A is a calling subscriber and desires his line to be connectedjii'ith that of the subscriber whose substation is indicated at C and whose number wilhbdassunied to be 2222.

Subscriber A, by removing his receiver to initiate a call establishes a path for a flow of current from ground through line relay 43. through contacts b3. the substation transmitter. the raised hook lever 5 through magnet 60, closed contact 62, orer line limb 66. armature to battery B. operating line relay :3, which. by armature 44, is locked to battery over the common conductor 73" and relay 73 of masterswitch l). The flow of current through the substation may 'momcntarilv actuate the magnet lit) to unlock dial 6 but as soon as pelav -l -l attracts armature 4ithe circuit -through thesubstation is interrupted. magactuating his calling device until his line shall have been brought ,into operative relation with the first selector F.

It will be seen that the multiple contacts 18 of thecalling line are grounded over conductor 32 and through normal contacts 53 and 46 as long as the line circuit of A is at normal, the said multiple contacts 18 being thus normally unselectable at the line selector. Attracted'armature 46, however, removes ground from the contacts 18 thus rendering them selectable and grounds the com ,mon conductor 50 energizing the group relay 47, which, by armature 49, removes ground from the group contact 31. As

soon as wiper 72 engages one of the segments 69 or 69", a circuit, is completed from ground through attracted-armature48 over the multiple contact 31.

attracted armature 76, armature 79, wiper 82 of master-switch D (wipers 80, 81. S2 of master-switch- D normally engaging contacts 83, 84, 85 of an idle line selector E) through contact 85 of such idle line selector, over conductor'39, closed oif-normal contact 86, normal-contact- 114, and the relay 90 to battery B, energizing the said relay 90. Since, as indicated by the location of normally engaged by the wiper 27, the calling line is included in the first sub-group of ten, no long steps of the line selector E are required to be made to select the calling line in the present case, so that the winding 10' of magnet 10 is not employed. but the stop magnet ll must be actuated at once and circuit must be closed through the short step winding 10 to initiate the short step travel of the switch. On the energization of relay 90. circuit is closed as follows: from battery B through magnet 14, through relay 97. contact 109. attracted armature 95', wire 127, normal contact 87. conductor 39 and to ground 'at segment 69 or 69 through interrupter l. .lttracted armature 93 has closed one break in the circuit of winding 10 and magnet His now actuated to close the second break therein and to throw the stop" pawl into operative relation with the mechanism of magnet 10.

Circuit may now be traced from ground through generator winding 10?. attracted armature of relay 14. alternate contact 93 to ground and magnet 10 will now bc actu ated by successive impulses from generator g'until the relay 90 is deenergizcd. each actuation of winding 10 producing a short step of wipers 2, 2, 25. 26 and 27.

It will be noted that on the first step of theswitch E. the off-normal. Oh. contacts were shifted to alternate position whereby electromagnets 14 and 97 were locked to ground via contact 89 by means of the attracted armature 100. Armature 103 of relay 97 has now connectedthe winding of relay 90 through alternate contact 94 and .normal contact 116 with the private wiper switch I) serves.

2 of the line selector, and since,on the first step of the line selector, contacts 86 and 87 are opened, the relay 90 now depends for its continued energization u'ponthe grounded contacts 18 to be encountered by wiper 2 as the wipers progress in their short step travel. Contacts 18 of non-calling lines will be grounded at armature 46 of their respective line relays -13, and since wiper 2 engages a new contact 18 before leaving the previously engaged one, relay 90 will continue energized until the switch wipers in their travel have reached a point where wiper 2 engages an ungrounded contact 18, such being one pertaining to the calling line. At this time, circuit through relay 90 will obviously be opened, the relay will become deel'nergized and its armature 93 being retracted, will prevent further actuations of winding 10 of magnet 10 and the wipers of the line selector E will come to rest. the wipers 2, 25 and 26 engaging respectively the multiple contacts 18. 2S and 29 of the calling line, that of A. ()n the retraction of armature 93. ground is placed via normal contact 93. alternate contact 102 and contact 111 upon the conductor 40 extending to the private contact 84: at the master-switch T). through its private wi or 81 and to battery through operating re ay 74, energizing said operating relay which opens contacts 78 and 79 to prevent any possible ground upon wipers S0 or 82. The armature 77 closes circuit for generator through motor magnet M of the masten switch. Vipers S0. S1, 82 being mounted upon a rotary shaft in operative relation with the driving magnet M. are rotated stcpby-step in search of contacts 83. 61. 85pertaining to an idle line selector. Contacts S-L of line selectors in use will be connected to ground and relay 70 will continue energized,

holding contact 77 closed until the masterswitch wipers cngage the contacts of an idle line selector. at which time the circuit for relay 7% will be open. the relay dci ucrgized. its armature retracted and wipers 80, 81. 82, will rest engaging the contacts 8 64. 97 of such idlc line selector and rcady to start the same'whcn another call is initiated from one of the lines of the group that the master- As soon as rclay 90 was first operated, it closed altcrnan: contact 91 whereby a flow of cnrrcut was produced from the positive side ol' lll tll'l'y Fig. 1. Part 3. through relay l l. normal contact at 16.), over conduct; r 190. conductor 123, normal contactllii, conductors 1522-121. normal contact 172, relay Sll to the active side of battery B relays- PR and SR being thereby energized. When now relay 90 is deiinergizcd as described. currcnt will find its way from battcry A through relay PR, normal contact 91. contact 2528, conductor 33, normal co tact 53, cut-oil relay 51 of the calling a-lin'e'A to battery, said relay 51 thereon energizing and by the closure of contact 53-- 53, locking itself to ground over conductor -32,-eonta ct-; 18-2, closed contacts 103, 116, and

normal contact 94 to ground. The 'a't94 placed upon the multiple contacts 18 ground through the 2.--has madethwmntacts. of. thecalling line unselectablc to othei line 45 is again closed and the ground on conductor 32' is extended. through said normal con tact 45' to. the multiple private contacts 56 of the line A at the; connectors, holding them grounded and unselectable. The said multiple contacts 56- were, on the initial operation of relay 43, grounded by attracted armature 45 so that the calling line was held busy against in-coming calls during the travel of the line selector E.

, On the actuation of relay 51, a circuit for relay PR was continued o er'conductor 67, current finding its return through conductor 66, conductor 34, contact 29 26, contact 96,

conductor 121 to battery B through relay SR whereby relays PR and SR have a substitute circuit completed for them upon the dce'nergization of relay 90 at line selector Ewithout either of'them permitting at any time theretraction of their armatures.

It is now apparent that the calling linehas, by the operation of the line selector E, had connected to it the relays PR and SR of the first selector F, paired with the line selector that was operated, and the said relays are .now controllable by means of the dial at the calling substation which dial was'unlocked as soon as cut-oft relay 51 operated, by the current holding relays PR and SR energized which traversed the magnet 60.

Before proceeding with a description of the operation of the first selector E and of the other directively operable switches, certain further explanation with respect to the line selt l or E is in order. The operation of this switch, when e calling line is in a sub-- group'other than the first. differs from that heretofore described in that-the long step winding 10' of the magnet '10 is employed to cause the line selectors wipers to select the sub-group in which the calling line is in eluded; wherefore the short step winding 10 is employed to select the individual contacts of the calling line out of the selected group. The wire 39 employed to start the line selector E, when the calling line is in the first group as hereinbcfore described, is not employed when the calling line is in any other sub-group than the first, the wire 41 being the starting wire for all other subgroups.

T have shown at 27 a sub-group relay for the second sub-group and at 4:7 a sub-group 5 j operati n ot relay 104, the relay 90 1S enerrelay for the third subgroup. The common tacts 46 of the ten line relays of the second sub-group, and the common conductor 5O hasbranches to the alternate contacts 46 of the ten line relays of the third sub-group, and it will be understood that there will be other sub-group relays 50, 50 etc., for the fourth, fifth, etc., to the tenth sub-groups with corresponding connections similar to those of relays 47 and 47". The conductor 36 at relay 4? connects'with the conductor 36 of'Fig. 1, Part 2, connecting to the multipEsUb-group contacts 31 of thesecond sub-group so the conductor 37, associated with relay 47*, connects to the conductor 37 of Fig. 1, Part 2, which is in connection with the multiple Sub-group contacts 31 of the third sub-group; a fourth sub-group contact 31 of Fig. 1, Part 2, of the fourth sub-group is shown and it will be of course understood that although but four sub-group rcrtacts a re shown associated with the wiper I.. there will in fact be ten such contacts, a (an responding number of sub-group relays l7 and a corresponding number of grounded segments for the wiper 27; also, that-although but three contacts 19 are shown as-- srciated with the wiper 2 of Fig. 1, Part 2,

there will be nine such between-group conof such line relay will remove the groundfrom the individual multiple contacts 18 of the calling line in the third sub-group at the line selectors, and Will close circuit to operate the subgroup relay/1:7 by current over the common conductor 50, while ar- Illiltll1'8 l5 will ground the multiple private contacts 56 at the connectors to render them busy. The operated sub-group relay 47*, by armature 49 removesground from the conductor 37 and from multiple sub-group contacts 31at the line selectors E. Armature 4S closes a bridge between conductors "TO and As soon asthe interrupter wiper T2 is disconnected from one of the segments (39 or. (39 and makes connection with one of the segments 71 or T1, circuit will be closed from ground over the conductor 70, closed 'ccntact l8". conductor 75, contacts 75, 78,;

--$ i conductor 41 of the line selector engaged by wiper 80, through contacts 88, 98, and relay 107! to battery l3. the relay 104 locking itself by armature 10? to ground \fia wiper 2?. multiple contact 31 of the first sub-group and contact 19, the relay being; unoperatcd because the call is'not that (f the line of the first sub-group. \Vith the 6 conductor 50 has branches to alternate conl gizcd by current through attracted armature 105. The stop magnet 14 and relay 97 are, however, not operated at this time, contact109 being open. When now wiper 72 of interrupter I passes over contact 69 or 69, current impulses will flow over the con doctor 38 through contacts 108, 101 and winding 10' of magnet 10 to battery and obviously, the continued travel of wiper 7 2 and successive actuationsof winding 10 will be produced. as long as contacts 108, 101 remain closed. The first impulse through winding'10' effects a long step of the wipers z, 2 25, 26 and 27 (the stop magnet- 14 not: having been energized as mentioned), and at the end of thigfirst step, of course, the wiper 2 will be. engaging the grounded contact 19, the wipers 2, and 26 will be between the first and second groups of their respective contacts 18, 28 and 29, and the wiper 27 will be engaging the multiple roup contact 31 of the second sub-group.

(T ince a line of the second sub-group is not calling, relay 47 will be inert, conductor 36 will be grounded at armature 49 and the relay 10t will continue energized by current. through attracted armature 107, contacts 27.-31", conductor 30, contact 49 to round. \Vith the Continued rotation of interrupter arm 7 2,v another impulse will be caused to flow through the winding 10 of magnet 10 and a second long step of the wiper will be effected at which time wiper 9. will engage contact 19*, wiper 27 will enga e contact 31 and wipers 2, 26 will be ac jacent to the third group of multiple contact sets. Contact 31' having been 'ungrounded by the operation of armature 49" of relay 47 of the third sub-group, circuit, for relay 10% is opened and the relay is deenergized, itsarmature 108 preventing further ac'tuations of winding 10 of interrupter I.

It will be of course understood that the off-normal contacts S0,' 87, 88 and 89 were all shifted to their alternate circuit conditions on the initial step of the switch, the opening of contact '88 making relay 10% en tirely dependent upon circuit through wiper 27 for its continued energization after the switch started.

On the deenergization of relay 104, relay 90 continued energized by current through normal contact 114, oyer conductor 125 and to ground through contact 219". The closing of contact 109 will now complete an energizing circuit for stop magnet 14 and relay 97 extending through attracted armature 95, over conductor 127, closed contact 106'and 89 to ground, whereon armature 100 of relay 97 closes a locking circuit to ground at closed contact 89. As described in connection with the selection of the calling line in the first sub-group, magnet 14 has now. thrown the stop into limiting position and has attracted its armature to close circuit from generator 9 through the short step winding 10 to ground through alternate contact 93. winding 10'-,'the resulting first short step of the wipers will open contact 2*19 so that the relay 90 will thereon depend for its continued energization upon circuits extending through alternate contact 94, con tactllt, contact 103, through the private wiper 2 and to ground upon multiple-con tacts 18 of non-calling lines. Relay 90 will therefore continue energized until wiper engages the multiple contact 18 of the calling line, which contact will be ungrounded, due to the attracted condition of armature 443 of line relay 43 of such calling line, deenergizing the relay 90 and the armatures of said relay will be retracted whereof 93 will open the circuit of winding 10 and wipers '2, 25 and 26 will rest engaging the multiple contacts 18, 28, 29 of the calling of course the wiper 2 will be somewhere between contacts 19 and 19 and wiper 27 -will be in engagement with the grounded contact segment between contacts 31 and before wiper 27 engaged such grounded segment, the relay 10% is inert.

tact at 91 caused the preliminary energizing circuit of relays PR and SR to be closed during both the long and short step travel of the line selector E. From the time the calling operations involved in holding energized the relays PR and SR, the energization of cutoff relay 51 which results of course in the deenergization of relays 43, 73 and of subgroup relay 47", and the moving along of the master-switch wipers 80, 81, 82, proceed in the manner before described.

' The selection of calling lines in the second, fourth, fifth and other sub-groups other than the first, will be effected in a manner apparent from the description of the selection of :1V line in the third sub-group, the operation being like that given except as to the point at which the relay 104 finds an ungroundcd sub-group contact 31.

Returning. now to the description of the connection between the calling line A in the bored thesubscriber at A operates his dial 05 to cause two breaks in the circuit of line limb 67, while line limb'66 remains grounded, the two said breaksbeing followed by one break in the circuit of line limb 06 while-limb G71remains grounded. Each break in limb 67 denergizes primary relay PR of Fig. 1, Part 3, relay SR remaining energized. On the first deenergization of i relay PR, an impulse of current flows from 1 ground through contacts 132-131, 141,1ok-

ing relay LR. to battery B, said relay LR,

On the first actuation of line of the third sub-group. At this time.

Itwill be observed that the alternate con- I line in the third sub-group is selected. the,

first] sub-group and the called line B, num- 31 but since armature 107 was retracted through contact 170, conductor 118 and contact'112. It will be remembered that in the directively operatedswitches such as first selector F, the winding of the stop magnet is normally in, the stroke limiting position.

On the energization oi? relay LR, the stop 'magnet 14 has a terminal of its winding connected respectlvely tobattery B and to ground through contacts 150 and 1 1-4. Said vmagnehis however, unenergized until after the relay PRis again operated at the conclusion of the first break in line limb 67 for the reason that the winding of magnet 14 is, while relay PR continues denergized, short circuited to ground through contact 135, contacts 140, 131 and 132. When, how ever, the break at contact 63 of substation A is closed and line limb 67 is thereby grounded via contacts 63, 61, relay PR en-' ergizes and the opening of contact'131 removes the short' circuit about magnet 14 and the said magnet energizes, withdrawing the stop and by armature 135, closing the long step winding 10* of the private magnet 10 to connection via armature 140 withthe contact of armature 131. The second de energization of relay PR which now follows, closes circuit from ground through contacts 132, 131, 140, alternate contact 135, winding 10 to battery and the magnet 10 thereon effects a long step of wipers 158, 159, 160 from engagement with the first set of multip'le contacts 161, 162, 163, of ten such sets assigned for connection to the first thousand of the exchange, to engagement with the first contact set 161, 162, 163, of the second group of contact sets, such sets being connected to second. selectors G :tor the second thousand of the exchange.

Having thus selected the group of second selectors, one of which is required to complete the desired connection to line 2229., the wipers 158, 159, 160, are now moved through short step travel to select the contacts of an idle second selector of the second group. This is efi'ected in response to the opening of line limb 66 at substation A, while line 67 remains grounded, which immediately follows the last opening of limb 67, as de-' scribed. Thereby relay SR will be deenergized while relay PR remains operated, and an impulse of current will flow from ground through contacts 130, 133, 119 and locking relay LR to battery, which relay, by armature 142 locks itself to ground at shifted offnormal contact 137. Armature 140 of course disconnects the winding 10* of magnet 1O from the upper talking conductor while armature 145 connects the winding of relay BR via alternate contact 151, with the private wiper 158 f the first selector. Armature 141 denergizes the step magnet 14 and the retraction of its armature ensues whereby the stroke limiting stop is placed in the path of the armature actuated pm; of magnet 10. Wipers 158, 1:30.160, ha ing, by the long step of the switch, been moved into engagemeutwith the first contact step 161, 162, 163*, short step travel of the switch F will be initiated only in case the first contact set .161, 162, 163 has already been rendered busy by some other first selector, in which case the private contact 161 will be grounded.

Assuming first that the first contact set is busy, current will flow from the grounded multiple contact 161 to wiper 158, attracted armatures 151, 145, relay BR andithrough resistance 7' to battery actuating the said re;

lay BR- before relay 150 has time to attract its armatures over acircuit which would be established, but for the energization of relay BR, via attractedarmature 1 13, normal contact 138 to ground through normal contact 136. Attractedhrmature 139 has now connected the generator circuit of the short step winding; 10 to ground via alternate contact 141-1, and stop magnet 14a"- being deinergized and the stop in, short steps of j the wipers 158, 159, 160 will be produced as long as the relay BR remains energized by successive circuits established. via wiper 158 and busy, that is, grounded contacts 161. As soon as the wipers of the first selector engage the multiple contacts of an idle second selector G, the contact 161 will be ungrounded, relay BR will have its circuit opened and its armature will be retracted, armature 139 preventing further actuations of magnet 1O while armature 138 will close a circuit as follows: from batter B through relay 150, attracted armature 113, normal contact 138, normal contact 136, to ground whereby relay 150 is energized and attracts its armatures whereof armatures 151 and 15% extend the. talking conductors of the first selector to wipers 159, 160 now at rest engaging contacts 162, 163 of an idle second selector. Armature 153 places ground upon wiper 15S whereby the multiple private contacts of the selected second selector are held busy. A circuit is then established from ground through attracted armaturcs 153, 151, 145 and through relay BR and resistance r to battery but this circuit is inclfective to energize the relay BR because of a short circuit at this time extending from point 156 to point 155 through contacts 146 and 152, which prevents suflicient current flowing through the relay BR to energize the same.

Had the first Set of contacts 161*, 162-,-

was, by the operation of armature 145, 0011- nected to the wiper 158. {)wing to the continued deenergizationof relay BR, no circuit for winding 10 is completed and relay 150 is at once operated via contact 1-13, normal contacts 138 and 136 to ground, the operation of the said relay 150 hating the effects before mentioned, that of grounding the multiple contacts of the second selector engaged by wiper 153, that of closing circuit through relay BR, and thatof establishing a short circuit about the one closed so that relay BR remains unoperated.

A clear circuit has now been established from condensers 173, '174, through contacts 151, 154v to the wipers 159, 160 and'the idle contacts 16:2, 163 and to the mechanism of the second selector Gr, assumed to be the one selected, which is now ready to be operated in response to the second set of deiinergizations of relays PR and SR to be produced by subscriber A by the further actuation of its calling device.

, Before proceeding with this, however, it is in order to refer to the operation of the first selector F.when its wipers 158, 159, 160

' are to be caused to select contacts of the first group of second selectors, those of the' first thousand. This operation differs. somewhat from that in which contacts of other groups are to be selected because no long step of the -wiper's 158, 159, 160 is produced, inasmuch 30 v tuation of thestop magnet 11- would follow as soon as the short circuit about its winding at armature 135 wasremoved on the subsequent energization of relay PR. The decnergization of relay SR following the single deenergization of relay PR results in the en- :ergization of locking relay- LR, as before described, the said relay now locking itself,

--.however, via armature 142, contact 137 13?, contact 147 and over conductor 118 to ground instead of to ground via alternate contact 137 as before. The wipers of the first selector-F have, in this case, remained at normal, andfrom this point on the initiation' of short step travel of the switch is produced in the manner before described and the selectionof idle contacts is effected in the same glue-liner as that before described, in

- case the st contact set, that normally enby wipers 158, 160 has been rendered busy. However, if the first contact set is idle at the time the relay LR isooperated,

relayv BR receives no current and relay 150 immediately energized, as before. described, by its armature 153 placing ground upon the first contact set that is aw assumed to be connected with a subscribers line in the first thousand of the exchange,

and if the first contact set of that thousand be idle, the first selector that is connected with the calling line is on a contact set of an idle second selector, and the impulses transmitted to the first selector, while producing the proper changes in theelectrical circuit of the switch, do not cause any travel of the switch wipers at all.

The calling subscriber at A now actuat es his dial 65 to produce breaks in the circuit fif limb 67 corresponding to the second digit of the called subscribers number, namely,

two breaks, whereby relay PR willibe twice deenergized and two impulses of current short-circuit about the winding of magnet j 11" extending via contact 183 and to ground through contacts 131 and 132- as long as relay PR is decnergized. Vith removal of this short circuit, however, magnet l attracts its armatures and withdraws the liniiting stop, armature 167 connecting the long step winding 10 of driving magnet 10? to ccnductor 165 via contact 183. T he' first impulse' transmitted -from conductor 165 therefore produces no steps of the wipers 201, 202, 203, and they remain engaging the first contact set 204, 20."), 206 of their first group of connectors, this being the normal The second dccnen position of the wipers. gization of relay PR transmits a current impulse over the before traced path through conductor 165 through normal contact 183,

alternate contact 167, long step winding 10 and to battery 13 whereby a long step of wipers 201, 202, 203 is produced and they are brought to engage the first set of contacts 204, 205, 206 of the group comiected to connectors for the second hundred lines of the second thousand. i

After the secogd deenergization of relay PR, a single denergization of relay- SR wlll of course be produced and an'impulse of current transmitted from ground through- I contacts 130, Q33, 154, 160,163 over conductor 166, contact 181, and lot-kin relay LR to battery-B, the saidrelay L then looking itself to ground at shifted off-norinal contact 190. Attracted armature 185 connects the winding of relay BRQyia alnd group. Assuming first that the set be- Y longs to a busy connector, it will be underwould have received no energizing current.

stood that the relay BR will be operated and armature 192- will prevent actuation of the relay 193 upon the denergization of magnet 1 1 which occurs as soon as armature 187 of the relay LR? was attracted. Stop magnet 14" being deenergized and its stop in, short steps of the second selectors G will be produced by current pulsations through the short step'winding 10 attractedfarmature 191 and alternate contact 187 to ground as long as relay BR remains opera ed, in which condition said relay will remain by current via wiper 201 and toground through successive contacts 201, multiple terminals of busy connectors,'until the wipers 201, 202, and 203 engage contacts 20 1, 205 and 206 of an idle connector. The contact 204 then engaged will be ungrounded, relay BR" will be denergized and its armature 191 will prevent further actua-- tions of the winding 105 whereby the switch wipers stop. Relay 193 now op erates by current through attracted armature 188, normal contact 192 and normal contact 108 to ground. Armature 195 of relay 1925 connects ground to the private multiple con tacts 2% of the selected connector of the second group, circuit being traced through wiper 201, points 199 and 200, attracted armature 195, attracted armature 177 of relay LR. to ground. The winding of relay BR is connected from battery at this time through alternate contacts 185, 178 and 200 with ground at attracted armature 177, but current over this path does not sufiiciently energize the relay Bltto cause it to attract its armature because of the short circuit extending around its winding from point'198 through attracted armatures 190 and 200 to ound. Had the first contact set of the second group been idle, the private contact 201 would have been migrounded and relay BR The relay 193 would, therefore, have immediately operated upon the energization of locking relay LRfl-and theattraction of its armature 188, by current through normal contact 192 and to ground through contact, 168 as soonas the magnet 14 cle'energized,v the relay 103 then placing ground upon the multiple contact'QOl, as before described, and closing-circuit through relay B11 with the accompanying short circuit to render it in'eiiective as described.

Had the calling subscriber desired his line to be connected with that of a subscriber included in the first hundred group of the second thousand, no long step of the wipers 201, 202, 208 would have" been 'pro- I duccd when relay PR was dener'gized a sin been -onuected to the pri'vhte wiper 201, vand ii the. 7

had been busy, the first-selector would have contuct sct of the first group had been idle, no travel of thewipers 201, 202, 203, would have been occasioned for reasons similar to those explained in connection with the first selector circuit diagram.

By the energization of relays Llt and LR and 103, a clearcircuit has been established from coiulensers 1.73, 171 at F over the conductors 165, to wipers 202, 203, and toe multiple contact 20.3, 2013 of the selected connector assumed tolie-the one shown at H, and over its wires 208, 209 to the mechanism thereof.

dial (l5 to produce two deenergizations of relay Pltrepreseniing the tlurd digitin the, called subscribers number, which deeneu l i ll d b t l d gmations \.i .36 .0 one 3, no sin e e traced circuit to conductor 16?) thence via contacts 19-1, 20220Zr. wire 208, normal contact 219, locking relay LR to, battery conductor 20?. Armature 216 of relay connects battery B through stop magnet 11 with ground, but the stop magnet cannot be driving magnet 10 until a short circuit at selector l* is removed on the energization of relay PR, the said short circuit being trace- .magnet 14 and normal contact, 218. As

and magnet 11 actuated to withdraw stop from the path of the driving pawl. On

the Second dei uergization of relay PR,

10 and to battery 15" producing a 1011 step of the switch wipers 2-19, 250, 2.31 to a pos started on short step travehin amanner obvious iroui what has preceded, to select idle contacts oi the first group. It the first energized to withdraw the stop pawl of closed contact 132 of relay SR of the first able from the normal armatureContact of soon, however, as the firstimp 'ilse over wire. 208 ceases, the short circuit will be removed I therefore, the transmitted current impulse will flow over conductor 208, through nore Inal contact 218, attracted armature of magnet 11, the longstep winding 10 of magnet;

tion adjaccntto the second group 01 ten attracted armature 215, locking relay LR gle time. ll'hen relay SRwas thereafter de-w energized, the busy relay BR wouldhave i'n'stfcontact setof the first group The calling subscriber it now operates his cncrgization of SR. On the first deenergiza- 1.101101 relay 1 l, a current impulse 1s transmitted irom ground over a, betorc. :95,-

B which relay operates and, by armature 21 i, locks itself to ground over the private to bat 'fisnd'saikllom "relay-brainsture2 2 tl ibnnects its windingto at %e shifted ofi-normalspring contact 211'. 41th circuit of stop ma et=14 and the said gnet isdeener its rettacted tlrmature'placing the stop limiting osition.

The su scriber A -in-=the circuit of v lineconductortf followed by line conductor 66. The first reak in conductor 67 of course decnergizes relay PR and an impulse is transmitted from ground 15 over conductor-208, a part of the cln'rent flowing throu h alternate contact 218 and locking relay iRT- whichfener es, and. by 'armature 224, locks to'groun at alternate contact 217. The rest of'this first impulse 2d flows through alternate contact 219, contact 212, oont-act 241 and the winding-1,0 of ma et j10, 'causin an actuation thereof; vamf sinoe sto paw is. in, a first'short step of wipers 249, 250, 251, is produced. A- second impulse transmitted over conductor v 208 by the seconddecnergizatim of relay PR asses over the last tracedcircuit ineluding alternate contact 219 and the winding 10' of relay 1Q-and a aeofond'short step of the wipers 18 produced, which will then engage the second contacts of the second group,- the said contacts bein multipleterminals ofline 2222-connecte ,to substation Q. A final'denergization'of relay SR foccuring by the opening of line conductor 66 now transmits a current impulse over conduct'or 209, through contact223', contact 239, the upper winding 'of test relay TR and to battery ener attraction o its armature 235, the lower of the relay TB is connected from battery tact 235, to ted'or private wiper 249, now engaging'the multiple contact '56s; of

- 'gized, armatum-236 actuated the-relay 238' which-,--by armature 240,- locked itselfto ground at alternate contact 217,-:tho-armature 239 openm T 1 .ln. call ed-for line is idle-mount I y tact j 56-- will 'be- .withltheg active .lflwef'w-in'ding of relay ileoeoitnected with the 'activesideiofsaid mum-mumm the retraction of the arma df fhy-'TR,-'a circuitii 'oom leted as.

iollottsjf h-oiii ground through ft e relay:

of-thscal dlinegfld'wbme through cut of lay lct actuatin'g thesai reldy'which,

racted armature '221 -1'mmediately' opens pa,w l in :theriiw '10 to produce two ope I one =in'the 'rupter I, alternately connecting ing the said relay. "Upon' the thrmgl conmtaao, alternate eon-:-

the called-for line. When relay TR en'er-' a 5 ple con-f fini edamseomba athsufp lyran a-v "tion.-, The clbsing-jof' contact' attracted" armature 242, no -mucous tact 235-, contact 24 9-56, normal'contact 45 56' upcii'the conductor 32 leading -tothe private banks at the line selectors,-whereby the called-for line remains unselectahlef'at the line- .sel'ectors. The ground multiple contact 56' from rela meanders the-called multiple contacts 5 57!, 58*0! the called line busy with respect to the-other connectors having-access to them; 1

; The winding of relay 24s now'h'as in a; 4

cuit closedfrom ground throulgh H stantly rotating interrupter attracted armature- 228, said'relay decnergized withv the travel of V with generator 9 when energized, relay '231- when denergized. The substation b'ellwill ring when generator 9 is connected with the wiper 250, the circuit bein traced through contact 57 over line lim .67, through call-bell and condenser at'the substation, returning "over conductor 66,

230 to battery. The'interruptersl and I 24s to batterfi-aud .rela'y- 248 .will vbe alternately ener 1 and-with contact '58", 251, arma-ture 229 and impedence" are preferably mounted upon the same shaft so' that their travel is synchronous and the interrupter I will the generator gfrom'the called lineand substitute therefor a short-circuit to ground a short period before "each denergization of relay 24 8 occurri'n with the rotation of theinterrupter 'I. T is arl'angement isitov secure a discharged condition of the'line circuit before;-

the relay 231 is placed -in connection therewith, in order to' with'certainty prevent said relay from being actuated by current dis-- charges from the .telephoneline and before the called, subscriber.

Thejcalled subscribed inanswering his callremoves his receiver and hook lever- 59 is; raised to-alternate position closing a conduetive bridge through the substation. As soon as' thisoccursand relay-231 is, by retraction of armature 248, connected with,

or 259 circhitmaybetttaced nu t malicontact' 2481, contact the said relay, co'ntact 22'z, nor- 25H? orver conductor-'61 ing'talkingmm 1 u;

tablishes'a branch g p fii foFthe-ie ion removes his receiver.

'ground-=at"=='altematecontact 217. v

armatures M L- 0ml: of;

cu t rihsthat fi many 

